JP2014032197A - Semiconductor element and method for measuring state of semiconductor material of semiconductor element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor element, a method for measuring the state of a semiconductor material of the semiconductor element, a measuring device, and the like.SOLUTION: A semiconductor element 108 to which at least one fluid component of a fluid is supplied includes: a substrate 110; an electrode 114; and a terminal 116. The substrate 110 composed of a semiconductor material 110 has a substrate contact 112 on a first side. The electrode 114 is arranged on a second side of the substrate 110, and is electrically insulated from the semiconductor material 110 by a chemical-sensitive insulating layer 118. The terminal 116, which measures voltage between the terminal 116 and the substrate contact 112, is arranged so as to be displaced to a side of the electrode 114 on the second side of the substrate 110. The semiconductor material 110 is doped so as to be conductive in an area of the terminal 116.

Description

  The present invention relates to a semiconductor element, a method for measuring the state of a semiconductor material of a semiconductor element, a measuring device, and a corresponding computer program product.

  In a chemically sensitive transistor, the transistor characteristic curve represents the relationship between the concentration of the material in the medium to be measured and the current flowing through the channel between the source and drain contacts of the transistor.

  DE102009045475A1 shows a gas-sensitive semiconductor device.

DE102009045475A1

  The object of the present invention is to solve the above-mentioned drawbacks of the prior art.

  In the light of the above background, a semiconductor device, a method for measuring the state of a semiconductor material of a semiconductor device, a measuring device, and a corresponding computer program product according to the independent claims according to the present invention are provided. Advantageous embodiments are described in the respective dependent claims and in the following detailed description.

  Semiconductor materials have electrical properties that can be influenced by the incorporation of impurity atoms having more or fewer electrons in the outer electron shell than the atoms of the semiconductor material. Impurity atoms are accommodated in the semiconductor crystal lattice during manufacturing (doping). This makes it possible to change the semiconductor material into different conductive states. Impurity atoms supply free charge carriers by unbound electrons or holes. Furthermore, the semiconductor material also has lattice defects in the crystal lattice, in which the atoms of the semiconductor material are constrained as a charge carrier, for example due to a difference in the arrangement of the lattice regions, without doped impurity atoms. Have electrons that are not. The properties of the semiconductor material in this lattice defect can be changed by interaction with the components of the supplied fluid. For example, the supplied gas component diffuses into the semiconductor material and occupies lattice defects. This can change the conductivity of the semiconductor.

  The charge carriers in the semiconductor material can have different energy levels. Thus, different magnitudes of force may be required to move charge carriers between these energy levels. This force can be brought about by an electric field, and the transferred charge carriers cause a current flow in the semiconductor. The higher the electric field, the larger the charge carriers can jump between energy levels. The component of the supplied gas contained in the semiconductor material can change the energy level from the initial position. In this regard, a stronger or weaker electric field may be required to cause the charge carriers to jump and move between energy levels. Therefore, when the component is accommodated in the semiconductor material, the presence of the component can be estimated from the current flow generated in the semiconductor material by the electric field. Based on the balance between the component amount in the semiconductor material and the component amount in the fluid, the concentration of the component in the fluid can also be estimated from the current flow.

  The semiconductor material can be exposed to an electric field between the two electrodes. A current flow can be detected between the first terminal of the semiconductor material and the second terminal of the semiconductor material. The present invention is based on the knowledge that a causal relationship exists between an electric field and a current.

The present invention provides a semiconductor device to which at least one fluid component of a fluid is supplied.
The semiconductor element has a substrate, an electrode, and a terminal,
The substrate is made of a semiconductor material,
The substrate has a substrate contact on a first side;
The electrode is disposed on a second side of the substrate and electrically insulated from the semiconductor material by a chemically sensitive insulating layer;
The terminal is for measuring a voltage between the terminal and the substrate contact;
The terminals are arranged on the second side of the substrate, shifted to the sides of the electrodes;
The semiconductor material is doped to be conductive in the region of the terminals;
A semiconductor device is provided.

  The substrate can have a disk shape. The first side of the substrate can be the bottom or mounting surface of the semiconductor element. The second side can be the sensor surface of the semiconductor element. The substrate contact can be an electrode directly connected to the substrate. The terminal can be a partial region of the substrate. The semiconductor material can be doped, for example, with an impurity material in the region of the terminal.

  The terminal can be formed in a ring shape around the electrode. The second contact can be formed in a closed ring shape or an open ring shape. In the case of an open ring shape, the influence of eddy current can be prevented.

  The substrate contact can be disposed on the main surface of the substrate on the opposite side of the main plane of the substrate on which the terminals are placed.

  The electrode and / or insulating layer can be configured to be at least partially permeable to at least one fluid component. Permeability can be understood as, for example, being porous, ie having a small hole pattern. The electrode and / or the insulating layer can be fluidphil or fluidskopisch. For example, the electrodes and / or insulating layers can attract fluid components and / or can be particularly well wetted by fluid components. Similarly, the electrode and / or insulating layer can have adsorption properties for fluid components.

The present invention further relates to a method for measuring a state of a semiconductor material of a semiconductor device based on the approach provided by the present invention,
Applying a voltage between the electrode and a reference potential; and
Detecting a current between the terminal and the substrate contact;
A specific step of identifying the state of the semiconductor device using voltage and current;
A method is provided.

  The semiconductor element can be supplied with at least one fluid component of the fluid. The voltage between the electrode and the substrate can generate an electric field, which can provide activation energy to change the energy level of charge carriers in the semiconductor material. The state of the semiconductor material can be understood as a state based on the interaction between the substance and the atoms of the semiconductor material, in which at least one characteristic of the semiconductor material changes compared to the starting state. doing. Such a state can be understood as a predetermined saturation of the semiconductor material, in particular of the substrate, for example due to a predetermined substance that diffuses from the fluid through the electrodes and into the substrate. Alternatively, this state to be identified can be understood as a local and partial reversible or irreversible change in conductivity based on the action in the substrate by substances from the fluid. The substance can be a component of a fluid in contact with the semiconductor element or semiconductor material. The state can be identified using processing rules. The processing rule may be a rule for combining the magnitude of the current, the magnitude of the voltage, and possibly another parameter, to determine the state of the semiconductor material.

  The voltage can be applied as a voltage pulse, which has a rising edge with a predetermined time rise from the start value to the target value. Alternatively or additionally, the voltage pulse can have a falling edge with a predetermined time drop from the target value to the start value. The start value and the target value can be voltage values. If the electric field between the electrode and the substrate contact is strong enough to provide the activation energy necessary to overcome the band gap, a controlled voltage rise or controlled voltage drop causes a current Can be detected. This allows the voltage value to be correlated with the current value. The voltage value can be positive and / or negative. Each edge can have a zero crossing.

  The voltage can have a predetermined first residence time at the starting value. Alternatively or additionally, the voltage can have a predetermined second residence time at the target value. The effect that can be detected at the rising edge and the effect that can be detected at the falling edge can be separated by a predetermined dwell time at the extreme value. These edges can also have a plateau to identify the state of the semiconductor material with small voltage steps.

  In the applying step, at least one other voltage pulse can be applied. In the detection step, at least one other current can be detected. By repeating the measurement, it is possible to detect a change in state relative to the preceding measurement. Thereby, the state change of the semiconductor material can be specified periodically.

  The further voltage pulse may have a different starting value and / or a different target value. The another voltage pulse may have another first residence time and / or another second residence time. Different characteristics and states of the semiconductor material can be specified by different minimum voltage values and / or maximum voltage values. If the voltage difference between the target value and the starting value is smaller than the potential difference required for the charge carriers to move from the valence band to the conduction band in the current state of the semiconductor material, the current band is It can be determined that the gap is larger than the voltage difference between the target value and the start value.

  The another voltage pulse may have a pulse shape different from that of the voltage pulse. For example, the edges can have different shapes. For example, one edge can extend linearly and one edge can be distorted into a sinusoidal waveform. For example, the voltage region can be made to progress more quickly or more slowly by making the edge region flatter and / or sharper so that a change in current that is likely to be delayed can be detected or omitted.

  In the detection step, the time transition of the current can be detected, and this transition can be detected over at least the voltage application time. By this transition, it is possible to identify an intermediate state in the semiconductor material that can be identified based on a state change in the semiconductor material.

  The invention further provides a measuring device adapted to carry out the steps of the method of the invention in a corresponding device. Also according to the embodiment of the form of the measuring device of the present invention, the problems underlying the present invention can be solved quickly and efficiently.

  The measuring device according to the invention can be understood as an electrical device that processes a sensor signal and outputs a control signal and / or a data signal depending on the sensor signal. The measuring device may have an interface that can be configured by hardware and / or software. When configured by hardware, the interface can be part of a so-called system ASIC, for example, containing various functions of the measuring device. However, it is also possible for the interface to be a unique integrated circuit or at least partly composed of discrete components. When configured by software, the interface can be, for example, a software module that resides next to another software module on the microcontroller.

  Program code that can be stored on a machine readable carrier such as a semiconductor memory, a hard disk memory, or an optical memory, when executed on a computer or device, the embodiment described above Also advantageous is a computer program product with program code used to implement a method based on.

  Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

1 is a block circuit diagram of a measuring device connected to a semiconductor element according to one embodiment of the present invention. FIG. 3 is a flowchart illustrating a method for measuring a state of a semiconductor material of a semiconductor device, according to one embodiment of the present invention. FIG. 6 is a diagram illustrating the voltage-time transition of a voltage pulse, according to one embodiment of the present invention. FIG. 4 is a diagram illustrating a current-time transition of a detected current, according to one embodiment of the present invention. FIG. 3 is a diagram illustrating atomic state changes in a semiconductor material during a voltage pulse, according to one embodiment of the invention. FIG. 6 is a diagram illustrating a characteristic map of a semiconductor device detected by applying a number of different voltage pulses according to one embodiment of the present invention.

  In the following description of the preferred embodiments of the present invention, the same or similar reference numerals are used for elements having similar functions shown in different drawings, and the description of these elements is not repeated.

  FIG. 1 shows a block diagram of a measuring apparatus 100 according to one embodiment of the present invention, to which a semiconductor element 108 according to one embodiment of the present invention is connected. The measuring device 100 includes an applying device 102, a detecting device 104, and a specifying device 106. The measuring apparatus 100 is configured to operate and test the semiconductor element 108. The semiconductor element 108 includes a substrate 110 including a substrate contact 112 (bulk contact), an electrode 114, and a terminal 116. The substrate 110 is made of a semiconductor material. The semiconductor material 110 can be supplied with at least one gaseous component of a gas when the gas flows. The substrate 110 has a substrate contact 112 on the first side. The electrode 114 is disposed on the second side of the substrate 110 on the opposite side of the first side. The electrode 114 is electrically insulated from the semiconductor material by the insulating layer 118. The electrode 114 and / or the insulating layer 118 can be chemically sensitive. The electrode 114 can be contacted via a contact. The terminal 116 is disposed on the second side of the substrate 110 and is shifted to the side of the electrode 114. The semiconductor material is highly doped in the region of the terminals 116 and thus has good conductive properties. The terminal 116 can be arranged in a ring shape around the electrode 114. The application device 102 is connected to the ground contact 120 and the electrode 114. The ground contact 120 has a reference potential. The application device 120 is configured to apply a voltage between the electrode 114 and the ground contact 120. The detection device 104 is connected to the substrate electrode 112 and the terminal 116. The detection device 104 is configured to detect a current between the terminal 116 and the substrate contact 112 as measurement information. A connection line between the terminal 116 and the detection device 104 is connected to the ground contact 120. The identification device 106 is connected to the application device 102 and the detection device 104. The identification device 106 is configured to identify the state of the semiconductor material 110 using voltage and current. The application device 102 includes a first voltage source 122 and a second voltage source 124 in this embodiment. The first voltage source 122 is configured to supply a low voltage (low voltage) as a voltage start value. The second voltage source 124 is configured to supply a high voltage (high voltage) as a target value. Switching between these voltage sources 122 and 124 can be performed by a switch 126 connected to the electrode 114. The application device 102 supplies measurement parameters by voltage.

  FIG. 2 is a flowchart illustrating a method 200 for measuring the state of a material component of a semiconductor device according to one embodiment of the present invention as illustrated in FIG. The method 200 includes an application step 202, a detection step 204, and a specification step 206. The method 200 can be implemented in a measuring device as illustrated in FIG. In the applying step 202, a voltage is applied between the insulated electrode of the semiconductor element and the ground contact of the semiconductor element. In the detection step 204, a current is detected between a terminal provided on the electrode side of the semiconductor element and a substrate contact provided on the side opposite to the electrode of the semiconductor element. In identification step 206, the state is identified using the voltage and current.

  In other words, FIG. 2 shows a method 200 for evaluating a chemically sensitive “transistor” without aggressive energization, and when the “transistor” is configured as an FET, the source terminal Is conductively connected to the drain terminal, so that no voltage control channel is formed under the gate. The method 200 can also be used in another semiconductor-based chemical gas sensor. The charge pumping method 200 based on the approach provided in the present invention is a characteristic evaluation method for evaluating a semiconductor-insulator-interface. This method can be used for process control and process evaluation during the manufacture of semiconductor devices such as the "transistors" described above. The method 200 can also be used during operation on a tested finished product.

  The gas supply in a chemically sensitive transistor changes the physical properties of the gate. In the finished product, transistor transfer curves are typically used to evaluate changes due to gas supply. The operating point of the transistor is shifted by the gas supply. In order to measure the transfer curve, it is necessary to energize by passing a current between the source and drain of the transistor. The method provided by the present invention omits the energization of this “transistor”. This is because no current flows in the “channel” under the gate electrode due to a short circuit between the source and drain.

  In the present invention, a separate base / bulk contact 112 connected to the current measurement unit 104 is required to measure the current flow. The source terminal can be short-circuited with the gate terminal. The voltage level between reference potential 120 and electrode 114 used in method 200 can be plotted. The approach provided by the present invention can be used with all semiconductor-based sensors with transistors, and in particular with semiconductor-based gas sensors with transistors.

  FIG. 3 is a diagram showing a voltage-time transition of a voltage pulse 300 according to one embodiment of the present invention, which voltage pulse 300 is applied to, for example, an electrode of the measuring apparatus of FIG. . The elapsed time is plotted on the horizontal axis of the diagram. On the vertical axis of the diagram, the voltage between the first contact and the second contact of the semiconductor element is plotted in order to measure the state of the material component of the semiconductor element as shown in FIG. . The voltage pulse 300 starts at a time t1 with a first voltage value that is a start value U1. The voltage pulse 300 has a rising edge 302 having a predetermined slope or time rise. At time t2, voltage pulse 300 has voltage U2 and exceeds flat band voltage Vfb. The flat band voltage Vfb is defined as a voltage where there is no band bending in the semiconductor material. At time t3, voltage pulse 300 has voltage U3 and is above threshold voltage VT. The threshold voltage VT is defined as the lowest externally applied voltage that induces a sufficient charge carrier concentration for charge reversal in the semiconductor material. At time t4, the voltage pulse 300 has a second voltage value that is the target value U4. In this embodiment, the rising edge 302 has a constant upward slope between the first voltage value U1 and the second voltage value U4. From time t4 to time t5, the second voltage value U4 remains constant. The residence time from t4 to t5 that remains at the second voltage value U4 is determined in advance. From time t5, voltage pulse 300 has a falling edge 304 with another predetermined slope or time drop. At time t6, the voltage pulse 300 has a voltage U3 and falls below the threshold voltage VT. At time t7, the voltage pulse 300 has the voltage U2 and falls below the flat band voltage Vfb. At time t8, the voltage pulse 300 again has the second voltage value U1. In this embodiment, the falling edge 304 has a constant downward slope between the second voltage value U4 and the first voltage value U1. In other words, FIG. 3 shows the pulse shape of the voltage applied to the electrode (to the gate).

  For example, the first voltage value U1 can be −4V. The flat band voltage Vfb can be set to −2V. The threshold voltage VT can be 1.2V. The second voltage value U4 can be 3V. It can be assumed that 0 unit time has elapsed at time t1. It can be assumed that two unit times have passed at the time point t2. It can be assumed that at the time point t3, 5 unit times have elapsed. At time t4, it can be assumed that 7 unit times have elapsed. At time point t5, 93 unit hours can elapse. It can be assumed that 95 unit time has passed at the time t6. It can be assumed that 98 unit time has passed at the time t7. It can be assumed that 100 unit time has passed at the time t8.

  FIG. 4 is a diagram illustrating the current-time transition of the detected current 400 according to one embodiment of the present invention. As in FIG. 3, the elapsed time is plotted on the vertical axis. 3 and 4 show the same time segment. On the horizontal axis of the diagram, the current value between the terminal of the semiconductor element as shown in FIG. 1 and the substrate contact is plotted. The current 400 starts at the current value I1 at time t1. After time t1, the current 400 drops with an approximately constant down slope. At time t2, the current 400 has a current value I2. Until time t3, the current 400 remains constant at the current value I2. After time t3, the current 400 rapidly rises to the current value I1, and then remains at the current value I1 until just before time t6. After the time point t6, the current 400 increases to the current value I3. The current 400 has a rising edge between the current value I1 and the current value I3. The rising edge first rises steeply, then becomes flat, and finally rises again. The current value remains at the current value I3 until approximately time t7. After the time point t7, the current 400 drops from the current value I3 to a value slightly higher than the current value I1 until the time point t8. In other words, FIG. 4 shows the charge pumping current Icp400.

  For example, the current value I1 can be set to 0A. The current value I2 can be set to −1A. The current value I3 can be 2A.

  FIG. 5 illustrates the fill-release process at the energy level of the semiconductor material during a voltage pulse, according to one embodiment of the present invention. The semiconductor material has different energy levels between energy ranges 510 and 516 in different states. These energy levels are associated with a predetermined voltage potential. If the voltage applied in the applying step is greater than the potential difference between the two energy levels, the charge carriers are released, resulting in currents 518, 520 flowing in the semiconductor material. Reference numeral 502 indicates the filling process from the conduction band to the energy range. Reference numeral 504 indicates a partial emission from the energy range between energy levels 510 and 512 into the conduction band. Reference numeral 506 indicates a filling process with positive charges from the valence band to the energy range between energy levels 512 and 514. Reference numeral 500 indicates a partial emission from the energy range between energy levels 514 and 512 to the valence band of the semiconductor material.

  In each charge pumping cycle, a current pulse 300 as illustrated in FIG. 3 is applied.

  As soon as the threshold voltage VT is reached, an inversion channel is formed and the charge carrier concentration rises in the conduction band. Existing lattice defects can now be filled from the conduction band.

  If the edge falls rapidly, emission into the conduction band no longer takes place and emission in the direction of the valence band takes place.

  Depending on the corresponding time constant of the trap, different bands are filled and discharged. Current flows between the two electrodes by contact between the bands at different electrodes (source contact, drain contact, and bulk contact). This current is ultimately referred to as charge pumping current 400.

  If the threshold voltage VT or flat band voltage Vfb is not reached in the pulse, no charge pumping current flows.

  3, 4 and 5 are diagrams illustrating the basic concept of the approach provided by the present invention. A “transistor” having a shorted source terminal and drain terminal is pulsed in different ranges of accumulation and inversion to measure the operating point of the device. Since the element is not actively energized, the element is not thermally altered by the measurement, and the thermal load that is "stress" on the element is minimized.

  The determination of the device operating point is performed by measuring the recombination current 400. Recombination current 400 occurs only when the device is fully accumulated and inverted. This further has the advantage that the current consumption of the element 108 is reduced.

  It is also possible to implement a symmetric control with respect to the flat band, so that changes due to moving charge carriers are canceled out. The moving charge carriers are, for example, alkali ions present in an oxide located on the semiconductor. Alkali ions do not form a stable chemical bond with the oxide and can move freely from a predetermined temperature based on their size. Due to ionization, alkali ions follow an electric field induced by an externally applied voltage. When a flat band voltage is applied externally, the induced electric field in the oxide is equal to zero, and the voltage induces a positive or negative electric field above or below the flat band, which causes the movement of ions. Cause it to occur. As soon as the external voltage oscillates symmetrically around the flat band voltage, the ions quickly shift to each interface of the oxide at the same concentration. In this way, the influence of this charge on the overall control characteristics can be minimized.

  The characteristic curve obtained as a result is shown in FIG.

  A predetermined amount of charge carriers flows through the current measuring device 104 during each pulse. As a result, the current is proportional to the applied frequency in a first approximation.

  In the embodiment shown in the present invention, it is only checked whether the jersey pump current 400 flows. The voltage level is also changed to determine the operating point of the transistor.

FIG. 6 is a diagram illustrating a characteristic curve of a semiconductor sensor detected by a number of different voltage pulses according to a plurality of embodiments of the present invention. In this embodiment, the semiconductor sensor is a silicon carbide transistor. On the vertical axis, the first voltage value U1 as shown in FIG. 3 is plotted. On the horizontal axis, the second voltage value U4 as shown in FIG. 3 is plotted. In this embodiment, the first voltage value U1 that is the start value V _low is plotted in the range of −16.5 V to 0.5 V, while the second voltage value U4 that is the target value V _high. Is plotted in the range of -6V to 11.5V. The voltage values U1 and U4 can be supplied, for example, by the voltage sources 122 and 124 of FIG. Next to the diagram is a legend illustrating five different current value ranges of the resulting current (bulk current) when changing from U1 to U4. The first current value range has a value between 1.5 × 10 ⁻⁸ A and 1.0 × 10 ⁻⁸ . The second current value range has a value between 1.0 × 10 ⁻⁸ A and 1.0 × 10 ⁻¹⁰ . The third current value range has a value between 1.5 × 10 ⁻¹⁰ A and 1.0 × 10 ⁻¹² . The fourth current value range has a value between 1.5 × 10 ⁻¹² A and 1.0 × 10 ⁻¹⁴ . The fifth current value range has a value between 1.5 × 10 ⁻¹⁴ A and 1.0 × 10 ⁻¹⁶ . In the diagram, each value pair of the first voltage value U1 and the second voltage value U4 is associated with one current value from the above range measured by the device 104, corresponding to the legend. It is shown. At this time, a surface having the same current value range is formed. The measurement range 600 of the sensor is shown in the characteristic map. The measurement range 600 is a quadrangle, and the straight edges of the quadrangle are oriented obliquely. Within the measurement range 600, a line 602 representing the operating point 602 of the semiconductor device of FIG. Line 602 is oriented parallel to the longitudinal axis and extends through two opposite corners of measurement range 600. In this embodiment, the operating point 602 is at a second voltage value U4 that is 3V. No current flows outside the measurement range 600.

  These embodiments shown and described in the drawings have been selected as merely one example. Different embodiments can be combined with each other completely or in relation to individual features. One embodiment can be supplemented by features of another embodiment.

  Furthermore, it is also possible to repeat the method steps of the invention and to carry out in an order different from the order described.

  If an example includes an “and / or” conjunction that connects the first feature and the second feature, this example is an embodiment having both the first and second features, Embodiments having only the first feature or only the second feature can be included.

Claims (13)

In a semiconductor device (108) to which at least one fluid component of fluid is supplied,
The semiconductor element (108) includes a substrate (110), an electrode (114), and a terminal (116).
The substrate (110) is made of a semiconductor material (110), the substrate (110) has a substrate contact (112) on a first side;
The electrode (114) is disposed on the second side of the substrate (110) and is electrically insulated from the semiconductor material (110) by a chemically sensitive insulating layer (118);
The terminal (116) is for measuring a voltage between the terminal (116) and the substrate contact (112), and the terminal (116) is the second of the substrate (110). On the side, shifted to the side of the electrode (114),
The semiconductor material (110) is doped to be conductive in the region of the terminal (116);
The semiconductor element (108) characterized by the above-mentioned. The terminal (116) is formed in a ring shape around the electrode (114).
A semiconductor device (108) according to claim 1, characterized in that: The substrate contact (112) is disposed on a first main plane of the substrate (110);
The terminal (116) is disposed on a second main plane of the substrate (100) on the opposite side of the first main plane;
The semiconductor device (108) according to claim 1 or 2, characterized by the above. The electrode (114) and / or the insulating layer (118) is at least partially permeable to the at least one fluid component,
The semiconductor device (108) according to any one of claims 1 to 3, characterized in that: A method (200) for measuring the state of a semiconductor material (110) of a semiconductor element (108) according to any one of claims 1 to 4.
Applying a voltage (300) between the electrode (114) and a reference potential (120);
A detection step (204) for detecting a current (400) between the terminal (116) and the substrate contact (112);
An identifying step (206) that identifies the state of the semiconductor material (110) using the voltage (300) and the current (400);
A method (200) comprising: In the applying step (202), the voltage (300) is applied as a voltage pulse,
The voltage pulse has a rising edge (302) having a predetermined time rise from a start value (U1) to a target value (U4) and / or from the target value (U4) to the start value (U1). Having a falling edge (304) having a predetermined temporal drop;
The method (200) of claim 5, wherein: In the applying step (202), the voltage pulse (300) has a predetermined first dwell time at the start value (U1) and / or a predetermined second dwell at the target value (U4). Have time,
Method (200) according to claim 5 or 6, characterized in that. In said applying step (202), at least one further voltage pulse (300) is applied,
8. The method (200) according to claim 6 or 7, characterized in that: In the applying step (202),
Said another voltage pulse (300) has a different starting value and / or a different target value;
And / or
The another voltage pulse (300) has a different first dwell time at the different start value and / or a second second dwell time at the different target value,
The method (200) of claim 8, wherein: In the applying step (202), the another voltage pulse (300) has a pulse shape different from that of the voltage pulse (300).
10. The method (200) according to any one of claims 6 to 9, characterized in that: In the detection step (204), a time transition of the current (400) is detected,
Detecting the time transition (400) over at least the application time of the voltage (300);
Method (200) according to any one of claims 5 to 10, characterized in that   A measuring device (100) configured to carry out the steps of the method (200) according to any one of claims 5 to 11 in a correspondingly configured device.   Computer program product comprising program code for controlling or performing the steps of the method (200) according to any one of claims 5 to 11 when executed on a device or measuring device (100).